Electric-arc lamp



F. W. MILLER.

ELECTRIC ARC LAMP.

APPLICATION FILED MAR. 8, l9l9.

, 1 329 132 Patented Jan. 27,1920.

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FREDERICK W. MILLER, OF LOS ANGELES', CALIFORNIA,

ELECTRIC-ARC LAMP.

To all whom it may concern:

Be it known that I, FREDERICK W. MILLER, a citizen of the United States,residing at Los Angeles, in the county of Los Angeles and State ofCalifornia, have'invented new and useful Improvements in Electric-ArcLamps, of which the following is a specification.

This invention contemplates certain new and useful improvements in thefeeding mechanism of arc lamps, and is especially adaptable for use withthree carbons forming in effect a single are.

The objects of this invention are first, to provide feeding mechanismfor carbons which will simultaneously advance carbons at the same speed,thereby maintaining the are at a selected point; second, to provide amechanism which will feed carbons with a progressive uninterruptedmotion; and third, to provide details of structure, whereby a simple,durable, compact structure, easy to manipulate, is secured.

These objects will be more fully understood, as will also other objectsand cor responding accomplishments of my invention from the followindetailed description of a preferred embo iment of the invention. For thepurpose of this description reference is had to the accompanyingdrawing, in which:

Figure 1 is a side'elevation of the feed mechanism mounted in a floodlamp casing, the latter being shown in dotted lines; Fig. 2 is a frontelevation; Fig. 3 is an elevation on an enlarged scale of the feedplate; Fig. 4 is an elevation of the cover plate; and Fig. 5 is afragmentary section on an enlarged scale taken on the line 55 of Fig. 2.

The invention as disclosed herein is embodied in a three phasealternating current are lamp. Three carbons are brought together at asingle Point, each carbon being connected to one phase of the system.The result is that a single are in effect is formed at the meeting pointof the carbons, this arc being substantially constant in its lightintensity. Single arcs formed by taking current between any two of thethree phases will produce a flickering light depending upon thefrequency of the alternations. To overcome this, three arcs each on adifferent phase have been used, so that the phase relation of theflickering will produce in effect a constant intensity of light. Myinvention Specification of Letters Patent.

Application filed March 8, 1919.

Patented Jan. 2'7, 1920.

Serial No. 281,476.

is especially adapted 'to the use of three carbons and a single arc on athree phase system, although. not limited to such use.

Referring more particularly to Fig. 1, A indicates the lamp casing for aflood light, B the condenser and C the arc mechanism. It is usual tohave a means of focusing the are. In the present case this isaccomplished by having a hollow lug .6 in the nature of a sleeveattached to the lamp casing, and sliding therein a tube 7 to which thearc mechanism is attached, so that the arc may be advanced or retractedwithin the lamp casing. A thumb screw 8 serves to fasten or secure theare many focused posi tion.

Tube 7 is attached to a feed plate casing 9, and, at the other end isprovided with a hand knob 7 for'convenience in moving the arc mechanismwhen focusing. Within the feed plate casing 9 is a feed plate 10 mountedso that it may be rotated. For the purpose of rotating the feed plate ashaft 11 is attached thereto and extends through the tube 7 and knob 7,being provided at one end with a hand knob 12for convenience in itsmanipulation. The face of the feed plate is provided with a spiralgroove 13.

ecured to casing 9 is a cover plate 14, which also serves as a guide forcarbon feeder arms 15. As the feeder arms are duplicates of each other,only one will be described. Referring particularly to Fig. 5, feeder arm15 is square in transverse section and provided preferably with a shoe16 having teeth engaging the spiral groove 13. The cover plate 14 is"provided on its inner face with guide grooves 17 disposed 120 apart andso constructed that the feeder arms will slide therein. The cover platesecurely holds the feeder arms in position with the teeth in engagementwith the groove 13 in the feed plate. Secured to the feeder arm 15 is aholder arm 18, which is insulated therefrom. Any type of carbon holdermay be used, but I prefer to provide the ends of the arm with anenlargement of sleeve like form having a semi-cylindrical lip 20 securedthereto and a movable lip 21, which is forced against the carbon bymeans of a. thumb screw 22. The carbons 23 are placed in the holders andclamped between the lips 20 and 21.

The elements of the mechanism are so as sembled that the feeder arms 15are substantially the same distance from the center of the feed plate.The carbons are adjusted so that the arc will be formed in line with thecenter of thefeed plate. As the carbons burn away knob 12 is grasped andturned, thereby turning feeder plate 10. By rotating the knob in theproper direction the feeder arms will be'moved inwardly toward thecenter of the feeder plate following the groove of the spiral. Thisadvances the carbonstoward each other. It will be noted that there issimultaneous, uninterrupted progressivev movement of the carbons.

, Although I have disclosed aineans for manually adjusting-the carbons,yet my invention is not limited to this mode of adjustment. Automaticmechanism may be provided foiwa'dvancing and retracting the carbons,such construction coming within the scope of myinvention. Variousmechanical expedients may be resorted to without departing from myinvention, which res-ides particularly in the feeding plate and itscooperating parts.

\Vhat I claimds: V V 1. The combination in an arc lamp of a plurality ofcarbon-feeder arms, and a rotatableiplate-having a spiral way with whichsaid. arms are engaged whereby rotation of said plate-will move saidarms to and from eachrother, so as to uniformly feed the can bons to1acommon, point which determines the position of the are. r

The combination in a three phase are lamp-.of three carbon feeder arms,and a rotatable plate having a spiral way with which said arms areengaged, whereby rotation of said plate will move said arms to and fromeachv other, so as to uniformly feed the carbons to a common point whichdetermines the position of the arc.

The combination of a casing, a rotatable plate therein having a spiralway,.a plurality of carbon feeder arms having teeth thereon inengagement with said way, and a cover plate for said casing havingradial guides one for eachofsaid arms, whereby carbons are uniformly fedto a common point which determines the position of the arc.

4. The combination-of a slceve,a casing having an extension 'slidablymounted in said sleeve for focusing, a rotatable plate in saidcasinghaving aspiral way, a carbon feeder arm having teeth-thereon inengagement with sa1d way, and a cover-plate for said casinghaving aradial guide for said arm. 7

The combination of a sleeve, a casing having a tubular extensionslidably mounted in said sleeve for focusing, a rotatable plate mountedin said casinghaving a spiral way, a rod secured to said feeder plateand extending through said tubular extension for rotating said plate, acarbon feeder arm having .teeth thereon in engagement with said way, anda cover plate for said casing having a radial gu-ide for said arm.

In witness that I claim the foregoing I have hereunto subscribed my namethis 26th day of February, 1919.

FREDERICK lV. MILLER.

